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Unveiling the evolution:
Comparing fuel emission factors and primary energy factors in NCM/SBEM Versions 5 and 6

Comparing Fuel Emission Factors and Primary Energy Factors in NCM/SBEM Versions 5 and 6

Image: Dale Kelly/shutterstock.com | Description: Whitelee Windfarm, Eaglesham, Scotland

The New EPC Ratings: Comparing Fuel Emission Factors and Primary Energy Factors in NCM/SBEM Versions 5 and 6

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Updated software calculation assumptions have dramatically changed headline EPC ratings in Scotland since February 2023.

This article further discusses the broader context of these shifts, including the UK's commitment to reducing carbon emissions, the growing reliance on renewable energy sources, and the implications of these changes for environmental policy, corporate energy strategies, and sustainability goals.

We look at the reasons behind the cleaner grid-supplied electricity and the implications of higher Primary Energy Factors (PEFs) in V6 SBEM, and insights into the current state and future direction of energy consumption and carbon emissions in the building sector.

Carbon Factors

Carbon Factors, also known as emission factors, are essential components of energy assessment tools like SBEM and DSM. They quantify the carbon dioxide emissions associated with energy consumption in buildings.

We analysed data extracted from the most up-to-date NCM databases and looked at the significant trends in carbon dioxide emissions and primary energy usage across various fuel types, highlighting the progressive shift towards cleaner energy sources in the UK.

The increasing primary energy factors (PEFs) in the latest version of the V6 SBEM, compared to V5, raise interesting questions about the underlying factors contributing to these changes, including methodological updates, the evolving energy mix, and technological advancements in energy production.

Lighting

Illuminance levels for activities in NCM Activity

The database changed illuminance to minimum and maximum values. This article is to be updated with this information. The changes to the lighting in the calculation methodology have had a smaller effect on EPC ratings than the carbon factors.

Extracting the data from NCM

From the assumptions behind the old and new EPC calculation assumptions we plotted the data to create two graphs:

  • CO2 Emissions per Fuel Type (kgCO2/kWh): This bar graph compares the carbon dioxide emissions for various fuel types, as measured in kilograms of CO2 emitted per kilowatt-hour of energy produced. The comparison is made between two versions of the SBEM (Simplified Building Energy Model) calculation, versions 5 and 6.

  • Primary Energy Factors per Fuel Type (kWhPE/kWh): This graph displays the primary energy factors for different fuel types. Primary energy factor is a measure of the amount of primary energy (in kilowatt-hours) required to produce a unit of delivered energy (also in kilowatt-hours). Again, the comparison is between SBEM versions 5 and 6.

These graphs provide a visual representation of the environmental impact of different fuel types in terms of CO2 emissions and energy efficiency, as quantified by the primary energy factors.

EPC ratings in Scotland have improved for non-domestic buildings

Why is grid-supplied electricity cleaner in the UK now than 10 years ago?

The trends observed in the data from the spreadsheet, particularly for grid-supplied electricity, likely reflect the broader shift in the UK's energy landscape towards cleaner and more sustainable sources.

Key trends and reasons why grid-supplied electricity in the UK is now cleaner than it was a decade ago.

  • Decrease in Carbon Intensity: The CO2 emissions per kWh for grid-supplied electricity have decreased over time. This trend is primarily due to the gradual phase-out of coal-fired power plants and the increasing reliance on renewable energy sources like wind, solar, and hydroelectric power.
  • Increase in Renewable Energy Sources: The UK has made significant investments in renewable energy over the past decade. Wind power, in particular, has seen substantial growth, with offshore wind farms contributing a significant portion of the country's energy mix. Solar power has also expanded, aided by technological advancements and decreasing costs.
  • Reduction in Coal Usage: Coal, once the backbone of the UK's electricity generation, has seen a marked decline due to environmental concerns and carbon pricing. The UK government has committed to phasing out unabated coal power by 2024, significantly reducing CO2 emissions from electricity generation.
  • Improvements in Energy Efficiency: Advances in technology have led to more efficient power generation, transmission, and usage. Improved efficiency reduces the total amount of energy required to meet the country's needs, thus lowering the overall carbon footprint.
  • Government Policies and Targets: The UK government's commitment to reducing carbon emissions, as part of international agreements like the Paris Climate Accord, has driven changes in the energy sector. Policies promoting renewable energy, carbon pricing, and emission reduction targets have all contributed to a cleaner electricity grid.
  • Public Awareness and Corporate Responsibility: Increased public awareness about climate change and environmental issues has increased demand for clean energy. Many corporations are also adopting sustainability goals, pushing the demand for renewable energy sources.

These factors combined have contributed to a significant reduction in the carbon intensity of electricity generated in the UK, making grid-supplied electricity cleaner than it was ten years ago. The shift towards renewable energy sources, along with policy support and technological advancements, have been pivotal in this transition.

Why are many of the primary energy factors higher?

The increase in primary energy factors (PEFs) in version 6 (V6) of the Simplified Building Energy Model (SBEM) compared to version 5 (V5) likely reflects changes in the methodology, updated data, and a shift in energy sources. PEFs are used to estimate the total energy used in the production and delivery of energy to a site, including losses in generation, transmission, and distribution. The reasons for higher PEFs in V6 SBEM could include:

  • Updated Calculation Methodologies: Each version of SBEM might use different methodologies or assumptions to calculate the primary energy factors. If V6 incorporates more comprehensive or updated methodologies that better account for energy losses or other factors in the energy supply chain, this could result in higher PEFs.
  • Changes in the Energy Mix: The energy mix in the grid changes over time as different sources of energy (like renewables, nuclear, gas, coal) contribute varying amounts to the total energy produced. An increase in the use of energy sources with higher primary energy requirements (even if they have lower CO2 emissions) could lead to higher PEFs.
  • Inclusion of More Factors in the Calculation: If V6 includes additional factors in the calculation that were not considered or were underestimated in V5, such as transmission losses, energy used in the maintenance of energy infrastructure, or the lifecycle energy costs of energy sources, this would increase the PEFs.
  • Energy Source Efficiency and Upstream Energy Use: The efficiency of energy sources and the amount of energy used upstream (like in the extraction, processing, and transportation of fuels) can vary. Changes or updates in these factors in V6 could lead to higher PEFs if the overall efficiency decreases or if the upstream energy use increases.
  • Policy and Regulatory Changes: Changes in energy policy, environmental regulations, or grid operation standards between the two versions could also influence the calculation of PEFs. For example, more stringent environmental regulations might require additional energy consumption for pollution control, thereby increasing the PEFs.
  • Technological Changes in Energy Production: Advancements in technology or changes in predominant technologies used in energy production can also impact PEFs. For instance, a shift from older, less efficient technologies to newer but more energy-intensive technologies in some phases of energy production could result in higher PEFs.

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